<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>Channel Coding Tools</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REL="HOME"
TITLE="LIBIT Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Programming with libit"
HREF="programming.html"><LINK
REL="PREVIOUS"
TITLE="Variable Length Codes"
HREF="vlc.html"><LINK
REL="NEXT"
TITLE="Channels"
HREF="channels.html"></HEAD
><BODY
CLASS="CHAPTER"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>LIBIT Documentation</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="vlc.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="channels.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="CHAPTER"
><H1
><A
NAME="CHANNEL"
></A
>Chapter 5. Channel Coding Tools</H1
><P
>      This chapter presents the various channel coding tools provided by libit.
  </P
><DIV
CLASS="SECTION"
><H1
CLASS="SECTION"
><A
NAME="MODULATION"
>5.1. Modulation</A
></H1
><P
>     Modulation consists in encoding a binary vector representing the message into a vector representing the physically emitted message. Currently only binary phase shift keying (BSPK) modulation is provided.
  </P
><P
>     BPSK modulation consists in coding each bit of the message with either a +1 (for bit 1) or a -1 (for bit 0) value.
  </P
><DIV
CLASS="EXAMPLE"
><A
NAME="CHANNEL-EXAMPLE-MODULATION"
></A
><P
><B
>Example 5-1. BPSK modulation example</B
></P
><PRE
CLASS="PROGRAMLISTING"
>  /* generate a random message of 10 equiprobable bits */
  bvec message = source_binary(10, 0.5);
  /* modulate the message using BPSK */
  vec modulated = modulate_bpsk(output);
  </PRE
></DIV
></DIV
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="vlc.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="channels.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Variable Length Codes</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="programming.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Channels</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>